And....that's a good thing?
If you've got young girls in your family, maybe about 1/8 of all families coming to WDW do, then you'll be glad, if you care about the financial health of WDW, then you'll be glad. A lot of fan boys think that Disney is expanding on the whole pantheon of princesses thing to personally insult them or something, its a business decision plain and simple, its OK IMHO that something like this is in the park as some guests really love them, that is what it is about: pleasing the guests.
Yeah, they took out SWSA for the meet and greet, but let's face it: WDW doesn't care to create great new dark rides, or even take care of the ones they've got, it's a lost art form in a way. Mermaid is something new, more of a "showy" musical ride, at least in DCA, meant for primarily little girls and grown up girls who were in love the Little Mermaid when they were kids. It's really just an animatronic Meet and Greet for Ariel as the final show scenes are incomplete/unfinished/horrible looking, and the ride doesn't have a soul and story of its own, just a musical revue.
The last couple good new rides Disney made are Splash and Indy in Disneyland, haven't ridden Radiator Springs Racers, while its dark ride portion looks promising, the golden age of dark rides has ended. (Though the Haunted Mansion Holidays is probably my all time favorite ride ever).
Given Mermaids shortcomings, the lack of dark ride elements on Toy Story Midway Mania, and the new trend with 7DMT and Big Grizzly having just a couple show scenes, TDO/WDI wasn't capable of upgrading SWSA, or even building what everybody is dying for: a Beauty and the Beast Dark Ride.
Might as well use the space for something else if they were just going to let SWSA rot away.
Disneyland is different, you've got a great Fantasyland with a lot of cool dark rides with heart . . . something about Mermaid is just hideously unwieldly and heartless given the size and poor/unfinished scenes.